Actually an object in JS stores string keys only, if you try to insert something else it's auto-converted to strings. Array is an object wich stores integer key

Actually an object in JS stores string keys only, if you try to insert something else it's auto-converted to strings. Array is an object wich stores integer keys. You don't really have a datastructure that stores arbitrary keys in JS (when not including third party libraries). This will be changed with Ecmascript Harmony though (dedicated Map type)